Spray gun



1950 F. NIEBURG 2,530,206

SPRAY GUN Filed Nov. 12, 1943 4 Sheets-Sheet 1 FIG; 3

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25 7 Inventor:

FELIX NIEBURG Attorneys Ndv. 14, 1950 F. NIEBURG SPRAY GUN Filed Nov. 12, 1943 4 Sheets-Sheet 2 inventor":

FELIX NIEBURG,

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Attorneys Nov. 14, 1950 NIEBURQ?j 2,530,206

SPRAY GUN Filed Nov. 12, 1943 4 Sheets-Sheet 3 \nvenfor:

F E-LIX NIEBURG By MM b Attorneys Nov. 14, 1950 NlEBuRG 2,530,206

SPRAY GUN Filed Nov. 12, 1943 v '4 Sheets-Sheet 4 FIG. 8 FIG! Inventor:

FELIX NIEBURG By wmw 5 PM};

Attorneys Patented Nov. 1 4, 1950 UNITED STATES ATENT OFFICE 2,53l206 SPRAY Gi ih Felix Nieburg, Stockholm, Sweden, assignor to Aktibola'get 'Golorator, Stockholm, Sweden, a

company of Sweden Application November 12, 1943, Se'ifial No. 510,012, Iii Sweden October 31, 1942 The present invention relates to a method and device for spraying liquids, such as paint-s, lacquers, varnishes, molten metal or the like, atomized to a spray jet by means of gas or air for surface coating purposes.

The main object of the present invention is to change, in connection with the indicated type of spraying, the cross section of the liquid-gas jet (here called the paint-air jet) by means of suction produced in the vicinity of said jet, particularl in the vicinity of the place where the jet discharges from the spraying device, said suction being adjustable and thereby enabling a continuous or step-wise adjustment of the cross SGCtiOri of the 1iquid=gas jet.

A further object of the invention is to achieve said suction by means of one or more separate gas or air jets, designated hereinbelow as suction jets or deformation jets, flowing in diverging directions relative to the paint-air jet or parallel with an at some distance from said jet. As the diverging suction jets have higher outflow velocity than the paint air jet there occurs a more or less injector-like suction action tending to increase the width of the paint-air jet. Due to thisdif= ference in velocity a space of reduced pressure is formed between the suction jets and the paintair jet, causing the width of the paint air jet to be increased in the direction towards the'suction jets.

Starting from a paint-air jet of originally cir cular cross section, a" further object of the invention is to increase the width of' said jet in one or more directions by meansof the suction jets so that a more lengthy cross section or a cross section of increased width in one or more directions is obtained. By arranging several diametrically opposed suction jet orifices in two planes perpendicular to each other an increase of the Width of the paint-air jet in horizontal or vertical direction may be' obtained as the suction jets disposed in oneof said planes or the other, respectively, are operated.

A still further object of my invention is to achieve very great jet widths by causing the suction jets to act upon a paint-air jet; which is originally somewhat compressed or flattened by means of a slotted nozzle, for instance. In such a case I dispose the outlflow orifices" of the sudtion jets diametrically opposed in positions corresponding to the direction of the major axis of the substantially elliptical cross sectionof the paint-air jet, and the action of the suction jets then cause anincr'ease of the width of the pair-itair jetin the direction of saidma cr axis. In

6 Claims. (Cl. 299*1401) this way great jet widths may be obtained. A further object of the invention is to arrange two suction jets diametrically opposed in the direction of the minor axis of the cross section also, so as to change the elliptical cross section towards a more circular shape.

A further object of the invention is to control the influence of the suction jets and consequently the width or the paint-air jet by adjustment of the outflow direction and/or of the pressure, quantity or the outflow velocity, respectively, of the suction jets.

My invention also comprises combinations with methods an means in which auxiliar gas jets are used for flattening or compressing the cross section of a liquid-gas jet. Thus, it is an object of the invention to further widen an originally flattened paint-air jet in the direction of the major axis by means of suction or deformation jets, and then by changing the outflow direction of said deformation jets and/or by means or separate pressure deformation jets again to compress the shape of the paint-air jet until it is more or less circular. The change of shape may he efiec'ted completely continuously or stepwise.

Since the outflow velocity of the suction jets is higher than the outflow velocity of the paintan jet, the suction jets act more or less as propulsion jets" according to U. S. Patent No. 2,247,000 dated June 24, 1941. Consequently, the inventi'on also includes embodiments involving difrerent combinations with the invention according to saidp'atent. However, separate propulsion jets may also be used together with or independ ently of the suction jets.

' The accompanying drawings illustrate as examplessom'e embodiments for carrying out'the method according to the invention.

Figure l is an external view of a spray gun according to the invention,

Figure 2' is a longitudinal section of the spray a Figure 3 is a front view of the spray head ac cording to Figure 2, v

Figure 4' is a dia'gr'ammatical longitudinal sec tion of a part of the spray head on a larger scale and illustrates the fiat-jet position of the deformation noZzle in which the deformation jets act as suction jets,

Figure 5 is a similar longitudinal section and illustratesthe position in which the deformation jets act as pressure jets;

Figures 6 and '7 are a longitudinal section and a front View, respectively, of another embodi' merit of the" spray head,

Figures 8 and 9 are similar views of a further embodiment, and

Figures 19 and 11 similar diagrammatical views of a modification.

In the several figures the same reference characters refer to similar parts.

With reference to Figures 1-3 compressed air is supplied from a suitable source to the spray gun (Fig. 1) through the pipe connection 1, and paint under pressure is supplied through the pipe connection 2 communicating with the paint receptacle 3. The supply of paint is controlled by means of a paint needle 4 (Figure 2) which is slidably mounted and is actuated in a known manner by means of a trigger member 5 (Figure 1). Preferably, the needle opens inwardly and in Figure 2 it is shown in its closed position. The needle may be guided by a sleeve 1. From the pipe connection I the air enters a chamber 8 from which it flows through a passage 9 and rectifiers m to an atomizing passage formed in front of the paint nozzle I2 in the atomizing nozzle I3. The velocity of this stream of air is controlled by means of a rotatable choke valve M. The casing |5 of the spray head is attached to the body IE of the spray gun by means of a threaded sleeve or nut II.

From chamber 8 the air is also supplied through bores I8 in the body If; and ports I9 in the casing l5 to a chamber 2|) within the deformation nozzle 2| which has projections 22 and is screwed into the casing |5 so that by turning or rotating the nozzle 2| in one direction or the other the position of the said nozzle may be adjusted axially. The rotation of the nozzle 2| may be limited by means of a stop screw 23 screwed into casing I5. Similarly, the whole spray head or hood may be rotated relative to body I 6 in order to adjust the position of the major axis of the spray jet as will be described, and this rotation may be limited by means of a stop screw 24 screwed into body IS. A spring 25' may be provided to establish a modified frictional resistance against the rotation of the nozzle 2| so that the latter will not be displaced unintentionally from its position.

The external end of the atomizing nozzle I3 is located after or externally of the mouth of the deformation nozzle 2|, viewed in the direction of flow.

If the paint needle 4 is retracted from the closed position shown in Figure 2 the paint from the paint nozzle I2 will enter the atomizing pas sage II in which it is atomized by means of the air entering the passage 9 and uniformly divided over the whole periphery of the said atomizing passage II by means of the rectifiers Ill. The mixture of air and paint discharges through a slot-like discharge orifice 25 or a narrow slit in the atomizing nozzle I3 so that the paint-air jet flowing out through the slot 25 will obtain the shape of a flat jet more or less elliptical in cross section. By rotating the spray head or hood I5 the slot may be adjusted from vertical position to horizontal position or any inclined position therebetween.

The air supplied to the chamber 20 in the manner described is intended to serve as deformation or shaping air, and to this purpose the outer surface of a member 26 has two diametrically opposed curved recesses 21, and two likewise diametrically opposed plane and inclined recesses 28. Between the recesses 21 and the inclined front wall 34 of the deformation nozzle 2| there are left openings 33 for the discharge of air from chamber 20. By adjusting the nozzle 2| axially the direction or the quantity of the discharged air may be controlled.

Through passages 30 in the member 26 the chamber 20 also communicates with a chamber 3| located around the nozzle |3. From the latter chamber air may discharge through an annular opening 32. This air serves as blowing air to keep the outer portions of the nozzle l3 and the member 26 free from drops of paint as described in United States patent application Serial Number 367,091 (now U. S. Patent No. 2,297,497).

In order to insure that the recesses 21 and 28 occupy accurate positions relative to the plane of slot 25 the member 26 and the nozzle |3 are interconnected by means of a guide pin 54 and associated with an inner extension 55 of the nozzle I3 by means of a nut 29.

The velocity of the air in the passage may be controlled by means of the choke valve M, preferably in such a manner that the velocity of the mixture of paint and air discharging from the slot 25 is the same or higher than the velocity of the air discharging through the openings 32 and 33.

The operation of the sprayhead illustrated in Fi res 2 and 3 will now be described with reference to Figures 4 and 5.

In Fig. 4 the front wall 34 of the deformation jet nozzle 2| has such a position relative to the recesses that the deformation air supplied from the chamber 20 discharges in diverging directions through the openings 33 along the paths B. The paint-air jet discharging through the slot 25 of the atomizing nozzle I3 would have the path indicated by the lines A and the elliptical cross section I, provided that said paint-air jet is not influenced by the deformation jets B. By the suction action of the deformation jets B, however, the width of the cross section of the paintair jet is extended, so that the cross section of the paint-air jet takes the resulting path indicated by the lines 0 and the elliptical lengthy shape indicated at II so as to form a wide or flat jet.

The maximum width of this Wide jet depends upon several factors, for instance the curvature of the recesses 21, the inclination of the wall 34 and the position of said wall relative to the axis of the atomizing nozzle I3, the angle 35 between the wall 34 and the cylindrical surface of the member 26, and the shape of the paint-air jet produced by the slot 25.

Fig. 5 shows the effect of opening the air outlet area formed between the inclined plane recesses 28 and the inner wall 55 of nozzle 2| by means of forward displacement of said nozzle. Thereby the deformation jets take a converging direction, as illustrated by the lines B and compress the paintair jet discharging from the atomizing nozzle, which originally has a path confined by the lines A and a cross section indicated by the ellipse P, so that said jet takes a more circular resulting shape 11 confined by the lines C Between said extreme positions of the shaping jet nozzle 2| relative to the atomizing nozzle |3 which produce jets having wide or circular cross section, respectively, the deformation jet nozzle may be set into any position, and consequently continuous adjustment from wide to circular jets may be obtained.

Figs. 6 and 7 illustrate a further embodiment. In this embodiment the paint needle 4 opens outwards but the atomizin may be effected in mainly the same manner as in the two embodiments already described. Furthermore, the deformation or shaping of the atomized paint-air jet by means of the suction jets is effected in two steps.-

In the proximity of the atomizing nozzle l3 there is a first deformation nozzle 4| screwed into a separating wall 42 of the casing l5 so that the nozzle 41 may be displaced axially so as to control the direction and/or the quantity of the air discharging through the openings 43. These openings may be formed in substantially the same manner as the openings 33 in Fig. 2. The air to the openings 43 is applied from a chamber 44 communicating with the passage l8 through the port [9. Behind and outside the nozzle 4| there is a second deformation nozzle 45 which is screwed adjustably into the casin l5 and contains a chamber 46 communicating with a separate source of compressed air through apipe connection 48 having a control valve 41. The suction air supplied to the chamber 46 discharges through openings 49. The suction air jets discharged through openings 43 and 49, respectively, are adjusted so as to produce a greater suction action for the jets through openings 49 than for the jets through openings 43.

If the paint-air jet dischargin from the slot 25 is not influenced by any suction jets it takes the path A and the cross section I. The suction jets B from the openings 43 produce a first increase of the Width of said jet A so that it assumes the cross section II, provided that there were no further suction jets. A further widening of the cross section of the jet'A, however, is

effected by the suction jets D discharging from the openings 59 so that the paint-air jet finally obtains the resulting wide cross section III and the path C. Thus the shaping or deformation of the wide jet C is effected step-wise. Of course, more than two steps may be used in order to attain the'desired result.

According to Figs. 8 and 9 the deformation nozzle 50 has a grip surface 5i and is provided with recesses 52, arranged diametrically opposed. The suction jet nozzle 56 is attached to the easing 58 by means of a nut 53 mounted so as to allow the nozzle 50 to be turned without operating the nut. The atomizing nozzle 59 has a discharge opening 60 which here is shown as a circular orifice. An annular recess BI is formed on the nozzle 59 in the vicinity of the front edge of the nozzle 58. It is thus clear that turning of the nozzle 50 will result in a turning of the plane containing the recesses 52 and thus also the discharge openings between these recesses and the annular recess 6|.

In the position shown in Fig. 8 the paint-air jet discharging through the opening 60 would have the path A and the circular cross section I if not influenced by any'suction' jets. The air discharging through the opening between the recesses Bi and the recess 52 as indicated at the lines B influence by suction the paint-air jet so that the latter obtains the elliptical cross section II with vertical major axis and takes the path C. If the deformation nozzle 50 is turned by means of the grip surface 51, for instance through an angle of 90, which may be performed without turning the nut 53, the paint-air jet will like wise be turned 90, so that the major axis of the elliptical cross section of the paint-air jet will be horizontal as indicated at IV. Between the position II and IV the said major axis may be set in any desired inclination.

During this adjustment of the position of the 6 major axis of the paint-air jet the angle of divergence of the suction jets B may be kept constant but it may also be varied. by displacing the deformation nozzle 50 axially on turning the nut 53 so that the front edge of said nozzle 50 changes its position in relation to the recess 6|.

Figs. 10 and 11 show an example of changing the paint-air jet from elliptical cross section to circular cross section by means of suction jets. The suction jets B discharge from openings formed between the front edge of the deformation nozzle 62 and recesses 64 on the external surface of the atomizing nozzle 63, while the paint-air jet discharges from the discharge slot 65 (here shown in horizontal position). The recesses 64 are arranged in the plane of the minor axis of the slot 6'5. It is clearly understood that the original elliptical cross section I of the paint-air jet A will be influenced by the suction jets B so that the paint-air jet will assume a more or less circular cross section II and follow the resulting path C.

As many changes could be made in the above method and construction and many apparently widely different embodiments of the invention could be made without departing from the scope thereof, as defined by the following claims, it is intended that all matter contained in the above description shall be interpreted as illustrative and not in a limiting sense.

What I claim is:

1. In a device for spraying liquids, for coating purposes, an atomizing nozzle for atomizing the liquid by means of gas to form an atomized liquidgas jet, and an auxiliary nozzle arranged in juxtaposition to said atomizing nozzle, said auxiliary nozzle having a discharge passage defining with the juxtaposed portion of said atomizing nozzle an outwardly-directed outlet for a gas-suction jet, the said passage being outwardly positioned relative to the said atomizing nozzle and having a jet-directing wall inclined outwardly relative to and beyond the outermost normal contour-defining limits of the liquid-gas jet, a common source of supply of air for said atomizing nozzle and said discharge passage, said discharge passage being smaller than said atomizing nozzle, whereby the velocity of the jet through said passage is higher than that of the jet through the atomizing nozzle and whereby the gas-suction jet is emitted in such a direction in relation to the contour of said atomized jet as to increase substantially the initial width of the latter jet by suction.

2. In a device for spraying liquids, for coating purposes, an atomizing nozzle for atomizing the liquid by means of gas to form an atomized liquid-gas jet, and an auxiliary nozzle arranged in juxtaposition to said atomizing nozzle, said auxiliary nozzle having a passage defining with the juxtaposed portion of said atomizing nozzle an outlet for a gas-suction jet, said discharge opening being outwardly positioned relative to the said atomizing nozzle and having a jet-directing wall inclined outwardly relative to and beyond the outermost normal contour-defining limits of the liquid-gas jet, a common source of supply of air for said atomizing nozzle and discharge passage, said discharge passage being smaller than said atomizing nozzle, whereby the velocity of the jet through said passage is higher than that of the jet through the atomizing nozzle and whereby the gas-suction jet is emitted in such a direction in relation to the contour of said atomized jetas to increase substantially the initial width of the latter jet by suction, portions of the surface of said atomizing nozzle which are juxtaposed to said auxiliary nozzle extending in different directions, and said auxiliary nozzle being displaceable relatively to said atomizing nozzle, whereby the direction of flow of said gas-suction jet may be varied by displacing said auxiliary nozzle relatively to said portions.

3. In a device for spraying liquids, for coating purposes, an atomizing nozzle for atomizing the liquid by means of gas to form an atomized liquidgas jet, a supply conduit for compressed gas communicating with said atomizing nozzle, and an auxiliary nozzle communicating with said supply conduit and arranged in juxtaposition to said atomizing nozzle, said auxiliary nozzle having a passage defining with the juxtaposed portion of said atomizing nozzle and outwardly directed outlet for a gas-suction jet, the said auxiliary nozzle being outwardly positioned relative to the said atomizing nozzle and having a jet-directing wall inclined outwardly relative to and beyond the outermost normal contour-defining limits of the liquid-gas jet, said discharge passage being smaller than said atomizing nozzle, whereby the velocity of the jet through said passage is higher than that of the jet through the atomizing nozzle and whereby the gas-suction jet is emitted in such a direction in relation to the contour of said atomized jet as to increase substantially the initial width of the latter jet by suction, and a control valve in said supply conduit for controlling the discharge velocity of said atomized jet,

4. In a device for spraying liquids, for coating purposes, an atomizing nozzle for atomizing the liquid by means of gas to form an atomized liquid-gas jet, and an auxiliary nozzle arranged in juxtaposition to said atomizing nozzle, said atomizing nozzle having a passage defining with the juxtaposed portion of said atomizing nozzle an outwardly directed outlet for a deformation jet in one position of said auxiliary nozzle, the said passage being outwardly positioned relative to the said atomizing nozzle and having a jet directing wall inclined outwardly relative to and beyond theoutermost contour-defining limits of the liquid-gas jet; a common source of supply of air for said atomizing nozzle and said discharge passage, said discharge passage being smaller than said atomizing nozzle, whereby the velocity of the jet through said passage is higher than that of the jet through the atomizing nozzle and whereby the said deformation jet is emitted in such a direction in relation to the contour of said atomized jet as to increase the initial width of the latter jet by suction, and the said passage defining with the juxtaposed portion of said atomizing nozzle and inwardly directed outlet for said deformation jet in another position of said auxiliary nozzle whereby the said deformation jet is emitted in such a direction in relation to the contour of said atomized jet as to decrease the initial Width of the latter jet by pressure.

5. The structure according to claim 4, said auxiliary nozzle containing a plurality of said discharge passages for saidgas deformation jets.

6. The structure according to claim 4, said auxiliary nozzle being rotatably mounted on said atomizing nozzle and containing a plurality of said discharge passages for deformation jets, and means to turn said auxiliary nozzle and said discharge passages relative to the axis of said liquid-gas jet to control the direction of said deformation jets for adjusting the cross-section of the liquid-gas jet.

FELIX NIEBURG.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,326,483 Doran Dec. 30, 1919 1,523,855 Barrows Jan. 20, 1925 1,962,911 Roselund June 12, 1934. 2,042,746 Tracy June 2, 1936 2,086,183 Gellner et al July 6, 1937 2,138,300 Gustafsson Nov. 29, 1938 2,228,226 Downs Jan. 7, 1941 2,247,000 Popofi June 24, 1941 

